JPS6095453A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain an excellent image by monitoring light and dark parts of an original part and generating a check pattern by a light source for exposure, and controlling an image forming means according to the pattern. CONSTITUTION:An exposure lamp 11 scans an original with a start signal, a detector 120 inputs values of light and drak parts of the original to a control part 130 successively, and only the maximum values Ll and Ld are stored in an RAM. The control part 130 sets the outputs of a power source 118 for primary electrostatic charging and a power source 119 for destatisizing to standard values. The exposure lamp 111 is set at the position of the check pattern (CP) 109, a driving power source 110 controls liquid crystal, and the transmissivity or reflectivity of the CP190 is set to Ll. In this state, the lamp 11 is varied continuously by a dimmer 112 and a surface potential is read in the control part 130 by a detector 121 and processed to determine the optimum quantity of exposure; and the light quantity of exposure of the exposure light source 111 is so determined that the value is obtained. Thus, an excellent image is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus designed to stabilize image quality.

To explain one embodiment of the image forming apparatus according to the present invention, first, in step 1, the states of bright and dark areas of a document are automatically read. Next, in step 2, the transmittance or reflectance corresponding to the bright and dark areas of the document is set in the image density check zone (or image density indicator) provided in the non-image area of the document table.

(1) Next, in step 6, the non-image area check zone (hereinafter referred to as a check pattern) on the document table is scanned or illuminated using an exposure source. During this scanning, the light that enters the photoreceptor is
the light source voltage or aperture so that it increases or decreases monotonically,
Alternatively, the slit width may be varied continuously or stepwise.

In this way, the reflected light (or transmitted light) of the check pattern part
The light enters the non-image area of the photoreceptor, and the portion of the photoreceptor surface that has been uniformly charged by the primary charger is neutralized by bright and dark area check signal light from the check pattern. As a result, an electrostatic latent image of light and dark areas corresponding to a check pattern is formed on the photoreceptor, and the photoreceptor is moved so that a row of nine bright and dark patterns is created in chronological order depending on the amount of light incident on the photoreceptor. . Next, in step 4, the electrostatic latent image of the check pattern row formed on the photosensitive area corresponding to the non-image area of the photosensitive member is read out by the latent image reading device, and the optimum exposure is applied to the photosensitive member under the usage environment of the photosensitive member. Determine. Next, in step 5, the electrostatic latent image contrast on the photoreceptor corresponding to the bright and dark patterns of the check pattern (2) under optimal exposure is calculated. Next, in step 6, if the contrast in step 5 is low, the power supply voltage applied to the primary charger is increased.

If the contrast is too high, lower it. This is repeated to determine the #primary charger applied voltage that provides the optimum contrast. Next, in step 7, an electrostatic latent image is created on the photoreceptor corresponding to the bright part of the check pattern under the optimum exposure amount.

For example, when an electrostatic latent image is read with a surface electrometer, the voltage applied to the charger for static elimination is varied so that the surface potential of the bright area becomes the optimum value, and the applied voltage value for static elimination is automatically determined.

By the above steps (1) to (7), Yp'Iff
, the latent image is stabilized, and it is also possible to remove capillary in the background area of the original, and even for an original with low contrast between the background and image areas, an electrostatic latent image can be created with considerably improved contrast than the original. If the concentration of the developer is always stable and the triboelectricity etc. are always at a constant value, the toner visible image created on the photoreceptor will be stable enough (3). A sharp image quality is formed on the photoreceptor. Normally, if the control is carried out to this extent, a considerable degree of image quality stabilization should be obtained, but the optimum values of the primary and neutralizing chargers are usually set empirically and are fixed values. However, this optimum value may vary depending on the usage environment or changes over time. Therefore, in step 8, the entire density image of the toner visible image of the bright and dark pattern on the check pattern formed on the photoreceptor is read by a 1111 degree detector, and the optimum value of applied voltage for static elimination is corrected based on the image density corresponding to the bright area. , the image density corresponding to dark areas, jl) Correcting the optimum value of the applied voltage for primary charging. By adding direct feedback from the toner visible image, the
Good image quality can be obtained. Further, we will specifically discuss embodiments of the present invention.

FIG. 1 shows an image forming apparatus according to the present invention as a copying machine (4). FIG.

In the figure, 101 is a photosensitive drum, 102 is a primary military corona charger, and 103 is a charger for static elimination.

104 is a full-surface exposure lamp, 105 is a developing device, 106 is a transfer charger, 107 is a cleaning grade, 108 is a document table, and 109 is a document light/dark portion check pattern.

109A is a bright area, 109B is a dark area, 110 is a check pattern control source, 111 is an exposure source, 112 is a light source dimmer, 113 is a second mirror (half mirror), 114 is a first mirror, 115 is a third mirror, 116 is a lens system, 1
17 is a fourth mirror, 118 is a power source for primary charging, 119 is a power source for static elimination, 120 is a light amount meter, 121 is an electrostatic latent image reading device, 112 is an exposure diaphragm, and 123 is an image density reading device on the photoreceptor. , 124 is a transfer roller, 125 is a fixing roller, 126 is a copy paper feed roller, 127 is a copy paper, 1
28 is the first feed roller +, 129 is the second feed p roller,
160 is a control device.

161 is a lens system, and 132 is a solid-state photovoltaic device.

For example, CCD (Ohargθcouplθti(lθ
via θ), BBD (backetbrigad
e clevice), etc.

(5) Figure 2 is a detailed diagram of a part of the copying machine shown in Figure 1, 201
202 is an effective image area of the document table, and 202 is a document density detector, one end of which is fixed to wire Y, and one end of which is attached to wire Y so as to be slidable. 206 is the exposure diaphragm slit on the back of the charger, 204 is the concentration detector drive clutch, 205 is the concentration detector drive motor, and the other numbers are number 1.
202 to 205 are the same as those shown in the figure, and 202 to 205 are exposure aperture 1 in Figure 1.
22 position.

FIG. 3 is a block diagram of the control section 130 shown in FIG. 1. In the same figure, Of'U is a processing circuit.

For example, 8 made up of 4040 (manufactured by Intel)
FIG. 4 shows a block diagram of the processing circuit OPσ.

M Engineering F is a memory interface, Example Ltd 42
It consists of 44 (inter cracks). RAM consists of memory 1, for example 4002 (manufactured by Intel),
The memo IJ RAM stores various data as shown in FIG. 0LOOK is a signal generator that applies a clock signal to the processing circuit OPU.

The above-mentioned elements are connected as shown in FIG.

(6) EU is an input device, which detects the surface potential of the photosensitive drum 1 with a probe P1 as shown in the detailed diagram in FIG. To be converted, multiplexer MPXA f
It is input to the converter A/D via. Further, the output of a probe P2 that detects bright and dark areas of the document and the output of a probe P3 that detects the toner density of the bright and dark areas are applied to the converter A/D via a multiplexer MPXA. Engineering H3O6 as the above multiplexer MPXA
0 (manufactured by Intasil), also converter A/f) tL.

A1570 (manufactured by Analog Devices) is used.

The output of Compartum/D is applied to multiplexer MPXDI. Furthermore, a signal from a copy start switch (not shown) and a copy stop signal are applied to the multiplexer MPXD2 as other inputs. The outputs of the multiplexers MPXJ)1 and MPXD2 are applied to the inverter NV1 via wired OR, and these outputs are applied to the buffer Buff shown in FIG. DE1 in FIG. 7 is a power bank (7) which selects the multiplexers MPXD1, MPXJ)2 and controls the inverter 1ff1.

In FIG. 6, OU is an output device W, a detailed view of which is shown in FIG. In the figure, L1 to L7 are latch circuits, which contain 4-bit and 2-bit storage elements, respectively, and are connected as a set of 4 bits. The latch circuits L1 to L7 described above are the buffers Bu in FIG.
The output of FF is set via the inverter NV2k. The decoder Dm2 outputs a signal to select the latch circuits L1 to L7.The outputs of the latch circuits L1 to L7 are connected to a primary charger via a converter that converts digital values into analog values and a D/A (for example, analog device #AD7550). Primary charge control circuit 1 (VT) that controls all the applied voltages of static electricity removal control circuit HVTB that controls the applied voltage of the static electricity removal charger
, an open-side single-circuit LDD that controls the monitor drive source 110,
a footlight control circuit IPL that controls the exposure light source dimmer 112;
It is applied to the drive circuit of the clutch 205 (not shown), the multiplexer MPXA to switch the output signals of the probes P1, P2, and P3, and the circuit shown below to start copying (8). Note on Figure 3!
The JROM stores instructions and data for executing control procedures as shown in FIG. DBS is memo IJ RO
This is a decoder that generates a signal for selecting M.

The operation of the embodiment having the above configuration will be explained with reference to the drawings.

When the start button of the copying machine is pressed, a copy start signal is generated, applied from terminal AO of multiplexer MPXD2, and confirmed by processing circuit OPU.
Enter the document scanning mode according to the control procedure stored in the OM. That is, the exposure lamp 111 is turned on at standard brightness, the document is scanned from end to end, and the values of the bright and dark parts of the document are sequentially added to the control unit 130 by the detector 120 (Boolob P2) and memorized. +7 Bright areas of the manuscript are stored in RAM (
Only the maximum values of Ll) and the dark area CL,i) of the original are left. That is, the maximum correction of both bright and dark areas is achieved during scanning of the original. This can be done, for example, by using a solid-state scanning photoelectric conversion device and inputting a signal to the control unit 130 (9), but for the sake of explanation, we will exemplify the method of scanning with one light-receiving element as shown in Fig. 2. Let me explain.

When the document table 108 is scanned and moved by υ in the direction of the arrow, the detector 202 (probe P2) provided in the slit 206 moves to the right as the clutch 204 is excited by the output of the latch circuit L7. From the perspective of the original, this means scanning the original at an angle in the direction of υ'. If the light-receiving surface of the detector 202 is to be read with a spot diameter of about 0.1φ, it should sufficiently hit the pack/ground portion and the character portion for a normal original document. Therefore, with this, the amount of light in the dark part of the original L
d. Bright area light amount L can be detected. Dark area light amount L
d. When the bright area light amount Lj is detected, the clutch 204 is turned off and scanning is stopped.

Next, the exposure lamp 111 is set at the check pattern position (as shown in FIG. 2). Next, the outputs of the primary charger application power supply and the charger application power supply for static elimination are set to Vp6. The control unit 130 outputs the standard value of Yes. At the same time, the photosensitive drum 101 is moved simultaneously.

In step 906, the check pattern 109 is
0) Ridge motion source 110 with transmittance or reflectance equivalent to the bright area of the document
Controls the LCD throughout. The data of this IJJ is stored in the memory RAM by steps 902 and 906. In order to set the transmittance, the check pattern control source 110 does not have to be a liquid crystal, but can mechanically create a pattern in which the transmittance changes by using an electrochrome or a motor, etc., and set it to something equivalent to IIJ. It's okay. In step 906, the density of the brightest part of the document is monitored using a check pattern. In this state, the dimmer 112 changes the exposure lamp 111 from low brightness to high brightness stepwise or continuously. As a result, check pattern 109
The amount of reflected i and Vps.

Due to VeB, the surface potential of the photoreceptor changes according to the jii-V characteristic shown in FIG. This surface potential is detected by the detector 121 (
The light surface potential value is sequentially read into the control unit 130 by the probe P1) and stored in the data memory RAM together with the exposure amount. From this stored data, the optimum exposure amount Hs is calculated as shown in FIG. This specific explanation was filed in June 1972 by the same applicant.
It is clearly explained in the automatic exposure apparatus of the patent application dated April 10th (11th), so to briefly explain it, the characteristic curve of the surface potential with respect to the amount of incident light exposure of the photoreceptor is shown in Figure 10. It becomes like this. When the slope drops to just 7% in order to adjust the optimum exposure t]rls, the shortcut becomes Ws. With a light source light cover of 88 or higher, the slope of the V- and + characteristics will change, resulting in a decrease in contrast, and [
8 or higher]: The contrast is sufficient, but the dynamic range is reduced. Therefore, as a light source light cover, E
8 is the optimal value. In step 2Q6, the optimum exposure amount under the usage environment has been determined.

As a result, the exposure source 110 passes through the output device fiiOU of the control unit and the υ light control device 112 so that the light amount becomes Is on the photoreceptor.
Set 0 light intensity. In this state, the optical system is scanned and the check pattern 109 is L! With the corresponding settings set, reflected signal light is applied onto a photosensitive drum suitable for the optimum exposure source. 9
09 is to create the drum movement time Tii which is narrowed when the drum reaches the detector 121 from the neutralizing charger 102, and the contents are stored in the register R1 (12) at regular time intervals to the accumulator AOO+1 and 1 hour T1 has elapsed. Detects the value when it reaches the desired value and issues a signal. The above elapsed values are stored in the memory ROM. Time T2 is stored in register R2.

The time T3 is stored in the register R3, and if the capacity is insufficient, it may be stored in the memory RAM. This is to provide a time delay for the detector 121 to read the value after the optimum exposure amount is applied to the light portion Ll of the original and reflected and the charge on the drum is removed. After T1 time, the check pattern 109 is set in the same way as LJ so that the transmittance or reflectance corresponds to the data part of the document. Step 912T2 is static eliminator 1
It shows the delay time required for the drum to move from o3 to the detector 121. In step 15, first Vpa, VeB
and a check pattern corresponding to the bright area of the original under the optimum exposure amount (
LII) The surface potential on the photoreceptor is read after the static electricity is removed by the reflected light from the photoreceptor and the entire surface is irradiated.

Let this value be VL. That is, the potential value corresponding to Ll is VL
becomes. After T2, the potential of the dark portion set in 910 reaches the detector 121, so that value is read.

(13) Let the value be iVd. By each step of 916 to 918, the standard surface potentials 1+h of the bright and dark areas are set to Vds and Via. Calculate the difference △vd, ΔML l from each value, and if it is within a certain error, the preset charger applied voltage is appropriate, but if it is outside the error, 919
, 920, the applied power supply voltages for primary and static elimination are calculated and corrected. Then return to 90B and IJI again,
II (1@Table 1m) Measure the potential and bring V'a and VL closer to Vda and VLa. When the surface potential falls within the difference from the standard value by step 918, the sleeve of the developing device 105 is removed by step 921. is driven to start development. T3 is the time during which the drum moves between the detectors 121 and 123. This allows development to occur with an appropriate electrostatic contrast and an electrostatic pattern without blurring. If you measure the image density of the toner visible image on the photoreceptor at that time, it should be close to the standard density Djs Dds of the light and dark areas, but due to changes in the characteristics of the photoreceptor, toner triboelectric changes, and carrier changes. Even if the electrostatic latent image pattern is close to the standard value, the image quality may differ (14).Therefore, the toner image density Dd corresponds to the dark area Ld.

Dark part L7! The difference-output ll is calculated from the corresponding toner image density DJ, and if it is outside the error, preset standard values Vdθ and Vltsf are corrected. Then, the process returns to step 208 and the voltages applied to the next charger and the static eliminator are corrected so that they become new Vds and V'/e. If the light intensity is good as a visible image in 928, you can start copying by step 931.
lights up to notify the operator that copying will begin. 966 is 1. from the original in the check pattern until the copying is completed. Jl', L(1@”
The process returns to step 908 and continues control so that each potential of step 4 is stabilized.

Figure 10 shows the -V characteristic, and the characteristic (2) is Vp.
When s and Ves are given, (1) is the characteristic diagram when the primary voltage is increased from the condition (2), and (3) is the characteristic diagram when the applied voltage for static elimination is increased from the condition (2). Show the diagram. As is clear from the figure, the primary voltage affects the contrast, and the neutralization voltage greatly affects the bright area potential. Therefore, in the present invention, the primary voltage is varied in order to increase the dark region voltage, and the static elimination type (15) voltage is varied in order to decrease the bright region voltage.

As is clear from the above explanation, according to Kien IJII, the electrostatic latent image is always kept constant even if the feather characteristics change under the usage environment, so i! Not only does the i+ quality remain stable, but it also monitors the bright and dark areas of the original, generates signal light directly from various exposure sources, creates a checking electrostatic pattern on the photoreceptor, and performs detection control to eliminate fogging on the original and eliminate images with low contrast. The resulting image is easy to read because it performs as many functions as possible in the tank. Moreover, since feedback is added after the toner is formed as a visible image, a very good image is ensured.

In the present invention, the brightness/darkness monitor of the document in the proportional #'i1 example may be performed using a method other than that described above, for example, by using a light source and controlling the exposure of the light source to a brightness corresponding to the brightness. -! As in the case of FIG. 2 or FIG. 1, an operator may scan the document using something like a light pen and store the light amounts IJ, L(l) in the memory.

In addition, in order to bring va, i closer to V(18,"its), it is dangerous to increase the primary (16) voltage and static elimination voltage too high to the extent that spark discharge begins. It is also possible to stop the copying operation with an alarm display.For example, VP in the middle of 220 and 219.

It is also possible to enter a different route and display an alarm when Ve exceeds a certain spark discharge starting voltage.

On the other hand, an isometric effect can be realized by fixing the applied power source for static elimination and controlling the developing bias.

Although the detector 121 in FIG. 1 has been described using a photoreceptor surface electrometer as an example, it is clear that any device may be used as long as it can detect the amount of charge held by the photoreceptor (electrostatic latent image).

The present invention has mainly been described with respect to a photoreceptor having a three-layer structure, but in the case of a three-layer structure, p' can be realized by the above method by using a developing bias instead of a charger for static elimination and excluding the entire surface exposure of 104. is clear.

In the above explanation, the part of the document monitor was described as a non-image part, but even if it is created in the effective image part, the effect of stable control of image quality can be obtained. It is clear that the latent image pattern does not need to be placed particularly in the non-image area, and even if it is formed in the effective image area, the effect of stable image quality control can be sufficiently obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a copying machine showing an embodiment of an image forming apparatus according to the present invention, FIG. 2 is a detailed view of a portion of FIG. 1, and FIG. 3 is a detailed block diagram of the control section shown in FIG. Figure IR4 is a block diagram of the processing circuit CPH in Figure 3, and Figure 5 is an area diagram showing the data area of the memory RAM in Figure 3. Figure 6 shows the processing circuit OPU, interface M engineering F,
Memory RAMD connection diagram, FIG. 7 is a detailed diagram of the output device OU shown in FIG. 3, FIG. 8 is a detailed diagram of the input device U shown in FIG. 3, and FIG. 9 is a detailed diagram of the memory ROM shown in FIG. 6. FIG. 7 is a flowchart diagram of a control procedure to be stored. FIG. 10 is a graph showing the relationship between the surface potential V and the element tB. P1-P3...Probe (18) ROM...Memory RAM...Memory Applicant Canon Corporation (19) Unexamined Japanese Patent Application Sho GO-95453 (9) Procedural Operator 11 Official Book (r1 issue) 1. Display of the case Special revision application filed in October, June 27, 1981 (1) 2, name of the invention Image forming device 3, person making the amendment Relationship to the case Patent 111 applicant address 3 Shimomaruko, Ota-ku, Tokyo -30-2 Name (100
) Canon Co., Ltd. Representative: Kaku 1i1, Part 3, 4, Agent address: Canon Co., Ltd., 3-30-2 Shimomaruko, Daime 1-ku, Tokyo 148 (telephone: 758-2111) 5, Statement subject to amendment 6, Contents of amendment (+) The claims of the specification are amended as shown in the attached sheet. (2) The 12th and 13th lines of the first page are corrected as follows. The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that allows highly accurate adjustment of image forming conditions. Conventionally, in image forming apparatuses such as copying machines, surface potential, density, etc. on a photoreceptor are detected, and charging conditions, exposure conditions, development conditions, etc. are controlled according to the detected values. However, even if the image forming conditions are controlled in accordance with the detected value by detecting simple shading, it has not been possible to adjust the image forming conditions with high precision. The present invention has been made in view of the above points, and an object of the present invention is to provide an image forming apparatus that can adjust image forming conditions with high precision. That is, the present invention provides an image forming device characterized by having an image forming means for forming an image on a recording medium, and a pattern forming means for forming a check pattern for adjusting image forming conditions by changing transmittance or reflectance. It provides I & equipment. Claims procedure amendment (method) November 29, 1982 (1982) Patent application for fraud No. 1322?5 Bow 2, name of invention image forming device 3, person making amendment Relationship Patent applicant office 3-30-2 Shimomaruko, 11th ward, University of Tokyo Name (+
00) Canon Co., Ltd. Representative: Ryu Kaku Sanbe 4, Agent Address: 3-30-25 Shimomaruko, 01-ku, University of Tokyo, 146 Leap.
Date of amendment order: October 30, 1982 (shipping date) 6. Specification and drawings subject to amendment

Claims (1)

[Claims] An image forming means for forming an image on a recording medium. a pattern forming means 5 for forming a check pattern by changing transmittance or reflectance; and a control means for controlling the image forming means according to the check pattern. An image forming apparatus characterized by having the following characteristics: